Groundwater issues stir up California agriculture

California agriculture in groundwater controversy over nitrate contamination.
Dairy, almonds and citrus growers are taking steps to cut down on unnecessary nitrogen use and improved efficiency in irrigation delivery systems for nitrogen and other nutrients.

Dennis Pollock | Jun 29, 2012

A Tulare meeting was pretty much expected to be a rubber-meets-the-road gathering on how growers can handle the challenge of cutting down on the amount of nitrates contaminating the groundwater below their fields while maintaining crop yields.

More precisely, it was a nitrogen-meets-the-root zone meeting, a look at what growers and dairy operators can do to maximize their use of nitrogen fertilizers, whether organic or inorganic, at the same time that they curb contamination of groundwater.

Industry presenters representing dairy, almonds and citrus talked of steps already being taken to cut down on unnecessary nitrogen use and improved efficiency in irrigation delivery systems for nitrogen and other nutrients.

Others, including the head of a coalition of growers facing tighter groundwater restrictions, discussed a need for more monitoring to establish base points that will show whether farmers are doing a better job of keeping nitrates from contaminating drinking water.

The program included some basic pointers on what needs to be done, along with some haunting questions on how agriculture can get to where its regulators – and itself — want to be when it comes to use of nitrogen to produce crops, milk and meat.

Here’s what some of the speakers had to say:

• “Nitrogen is slippery; it easily changes form and moves between environmental reservoirs,” said Paul Martin, director of environmental services, Western United Dairymen.

Dairies in the state have been active in adopting waste management and nutrient management plans, along with well monitoring at more than 4,000 sites, he said, and got an early start on groundwater protection.

Still, he said, the target of arriving at applying no more than 1.4 times the amount of crop removal, is “extremely difficult ... all has to go perfectly. Poor weather or bugs in crops can reduce yields and ruin the ability to hit the mark.”

Martin favors evaluating nitrogen efficiency as a “trend analysis over a period of years” rather than annually because of those kinds of setbacks.

He would like to see more research on ways to mineralize organic nitrogen as a way to making it more rapidly available to plants and sees that as a way to make it easier to transform manure into material that could be hauled away more economically.

Martin drew laughter as he said, “We could send it back to Nebraska where it came from.”

He also advocates testing for nitrogen in soils, irrigation water, crops and manure to properly balance nitrogen applications.

• “Spoon feeding nitrogen in multiple low doses” through delivery systems that include fertigation can be key, said Bob Curtis, associate director of agricultural affairs with the Almond Board of California.

Like Martin, he pointed to success in the almond industry as it has moved to more efficient delivery of nutrients with use of micro irrigation, timely leaf sampling, fertigation and application of nitrogen during periods of peak plant demand: “matching demand during tree growth and crop development.”

Curtis said self-assessment by growers can include quantifying how much nitrogen and other nutrients are used in production of a crop and what forms they take.

• “You can’t manage what you don’t measure,” said Andrew Brown, a Fresno County citrus grower and member of the California Citrus Mutual Executive Committee.

With a wife and two small children, Brown said it is in his personal interest to monitor water from the wells on his farm.

Brown said he turns to sources of information on “how to get more out of less” from the universities of Florida and Arizona, along with the University of California.

Less is more

Using too much nitrogen is a detriment, he said, producing fruit that is too large and less marketable: “There is no incentive as a grower to over-fertilize.”

Brown recommends soil samples at least every three years. He said differing varieties require different adjustments in fertilization, and said it’s important to “pinpoint physiological stages when a tree is mostly likely to pick up (the nutrients).”

A third of the fertilizer used in his operation is foliar. “We want to get nitrogen into the tree, not the ground and not the groundwater,” he said.

• Stuart Pettygrove, UC soils specialist, was among those who talked of the lack of uniformity in application of nitrogen using furrow or border irrigation.

He recommends using soil nitrate and plant tissue testing in forage systems. And he would like to see conversion of manure sludge and solids to organic fertilizers usable on a wider range of crops.

• Larry Schwankl, UC irrigation specialist, said one way of avoiding the lack of uniformity in furrow or border irrigation is to reduce the length of the field.

“Nobody wants to farm an eighth mile long field,” he said. But cutting back from a half mile to a quarter can mean more uniformity in irrigation and flow of nutrients. With micro irrigation, Schwankl said, “deep percolation losses can be minimized.”

• Growers need to establish realistic yield goals, said Bob Hutmacher, UC Extension specialist and director of the West Side Research and Extension Center.

Under typical winter rainfall and temperature conditions, he said, most nitrogen in fertilizer applied in ammonia forms would be converted to nitrate by planting time in the spring. That’s one of the reasons why fall or early winter applications are not recommended for a late winter or early spring planted crop.

Crop rotations matter. Hutmacher said rotations likely to produce higher soil nitrogen include cotton in rotation with shallow-rooted vegetable crops; garlic, processing tomatoes or field corn; and the first year after alfalfa.

Rotations likely to produce lower soil nitrogen include cotton in rotation with several prior years of cotton, small grains, safflower and sugar beets.

Hutmacher said anhydrous ammonia is slow to covert to nitrate in the soil.

Some stabilization products are being used outside California and could be beneficial, Hutmacher said.

Shallow groundwater system

• Growers in his region are confronted with a shallow groundwater system and increasing levels of nitrates, said Parry Klassen, executive director of the East San Joaquin Water Quality Coalition.

He is recommending that farmers in the coalition put together “nitrogen budgets” to keep tabs on nitrogen use as a benchmark. “Let’s find out what our crops are putting on,” he said. “I have faith we’ll show we’re doing a darned good job.”

Klassen said “wellhead housekeeping” using backflow preventers and preventing pooling of water will be a priority as a step to keeping unnecessary nitrates out of groundwater.

The coalition is also classifying particularly “vulnerable” areas.

• Asif Maan, with the California Department of Food and Agriculture and Fertilizer Research and Education Program, said the program is looking to do more outreach to growers and crop advisers.

Maan said a searchable research database went online July 1, making it easier for users to access information without having to wade through highly technical reports, though there are links for those as well.

He said users will be able enter search criteria that include a keyword, crop, county and date to get a summary of information.

The agency is also working with certified crop advisers to come up with a program to help growers implement nutrient management systems. It expects to have a program for training and added certification in place by December.

• Tibor Horvath, conservation agronomist with the Natural Resources Conservation Service, talked of assistance available through his agency.

He said in 2010 and 2011, the NRCS spent $782,061 to develop comprehensive nutrition management plans on 158 farms with 118,500 acres of crop land in the Central Valley through the Environmental Quality Incentives Program.

Some money was spent on more than 600 waste transfer pipelines and flow meters to transfer manure to fields of crops.

Money was also spent on cover crops that scavenge residual nitrogen and on manure separators, screen separators and settling basins.